Image forming apparatus having a main assembly, a cartridge detachably mountable to the main assembly, and a fixing unit detachably mountable to the main assembly

Abstract

An image forming apparatus includes a main assembly; a cartridge detachably mountable to the main assembly; a fixing unit detachably mountable to the main assembly; and an opening of the main assembly. When the fixing unit and the cartridge are mounted/demounted, the fixing unit passes through the opening, and the cartridge passes through a space in which the fixing unit is to be mounted and passes through the opening. When the fixing unit and the cartridge at the time of passing through the opening are projected onto a surface perpendicular to the mounting and demounting direction, a contour of a projected area of the cartridge is at least partly inside a contour of a projected area of the fixing device, and the cartridge passes through the inside of the contour of the projected area of the fixing device when passes through the opening.

1. An image forming apparatus comprising:
 a main assembly; 
 a cartridge, which is detachably mountable to said main assembly and includes a photosensitive member on which a toner image is to be formed, that operates so as to form the toner image on a sheet material in a state in which said cartridge is mounted in said main assembly; 
 a fixing unit, completely detachably mountable to said main assembly, that fixes the toner image on the sheet material; and 
 an opening that exposes an inside of said main assembly, 
 wherein said fixing unit and said cartridge are mountable into and demountable from said main assembly in a mounting and demounting direction in which said fixing unit and said cartridge are disposed side by side, 
 wherein, when said fixing unit and said cartridge are mounted into and demounted from said main assembly, said fixing unit passes through said opening, and said cartridge passes through a space in which said fixing unit is to be mounted and passes through said opening, and 
 wherein, when said fixing unit and said cartridge at the time of passing through said opening are projected onto a surface perpendicular to the mounting and demounting direction, a contour of a projected area of said cartridge is at least partly inside a contour of a projected area of said fixing device, and said cartridge passes through the inside of the contour of the projected area of said fixing device when passes through said opening. 
 
     
     
       2. An apparatus according to  claim 1 ,
 wherein said main assembly includes a first guide portion, at which said fixing unit is to be positioned inside said main assembly in contact with the first guide portion, for guiding mounting and demounting of said photosensitive drum with respect to said main assembly and includes a second guide portion, at which said cartridge is to be positioned inside said main assembly in contact with the second guide portion, for guiding mounting and demounting of said cartridge with respect to said main assembly, and 
 wherein the first guide portion and the second guide portion are formed on a common member. 
 
     
     
       3. An apparatus according to  claim 2 ,
 wherein the first guide portion has a first surface at which said fixing unit is to be positioned with respect to a substantially vertical direction in contact with the first surface, and the second guide portion has a second surface at which said cartridge is to be positioned with respect to the substantially vertical direction in contact with the second surface, and 
 wherein the first surface and the second surface are coplanar with each other. 
 
     
     
       4. An apparatus according to  claim 2 , further comprising:
 a transfer member, contactable to said photosensitive drum in a state in which said cartridge is mounted in said main assembly, that creates a transfer nip in which the toner image is to be transferred from said photosensitive drum onto the sheet material, 
 wherein said transfer member is disposed so that the transfer nip is positioned on an upstream side of a shaft of said photosensitive drum with respect to a direction in which said cartridge is demounted from said main assembly when said fixing unit and said cartridge are mounted in said main assembly.